Protecting means for transmission systems.



E. E. F. CRElGiTG-l. PROTECHNG MEANS For@ mmsmssmw SYSTEMS. APPLICATIONFILED MAY 14, 1913.

Wi Uw onerose,

ELMER E. F. GltEGl-ETON, 0F SCHENECT.F`DY, NEV YORK, ASSGNOR TO GENERALELECTREG CQMPANY, A CORPRAEEN Gli NEW YURK.

'LU EETECTING MEANS FSR TRNSMISSIQN SYSTEMS.

incassa l eppueaoen sied nay 14, i913.

To o whom it may concern:

Be it known thatl", Emmi; E. l?. Cnniorn 'r-oN, a citizen of the UnitedStates, residing at Schenectadyin the county of Schenectady, State ofNeu7 York, have invented certain new and 'useful improvements inProtecting Means for Transmission Systems, of which the following is aspeciiication.

ly invention relates to transmission systems and the object of myinvention is to provide for the protection of transmission systemsagainst the production and continnance thereon of certain unduly highvoltages and the prevention of oscillations of the energy thereon,Jproduced by the discharge of energy from or to one or more of 'theconductors ott the transmission system.

Various causes produce discharges of energy' between conductors of atransmission system, and between a conductor of a' tem and ground. Suchdischarges often take place through the air ,between a. groundedmetallic body and a conductor, or between conductors. Such an arc isoscillatory in character unless special provisions are made and as aresult gives rise 'to oscilla tions of energy on the system which arelikely to produce disastrous results to the attached apparatusA` as bythe building up of potential in a. manner Well understood. l accomplishthe object oi? my invention, as set forth above, by requiring that anecessary exchange of energy between conductors of a, system or 1oetweena conductor and ground take place at a certain point by reducing theinsulation value at this point or otherwise localizing the difflarge,and requiring that the disch-arg energy pass through a resistance ofapproximately the critical value. ln one aspect of my invention, it isimmaterial whether the discharge takes place from one conductor ofcurrent to another conductor of current, completing a icircuit throughthe arc, or Whether the discharge takes place between a conductor ot asystem of distribution, as one plate of a condenser, and anotherconducting body, as the earth, as another plate of a condenser. lneither case the discharge may be said to take place between twoconductors. As is well known, a discharge of electrical energy through aresistance of, or greater than, the critical value is aporiodic, hencesuch a discharge cannot produce oscillations ciI the Specification ofLetters Patent.

Patented May 8, 1913?, serial no. 767,543.

energy on the system. The critical value of the resistance, as is 'Wellunderstood, depends upon the inductance and capacity of the system as awhole, or the part of the system immediately related to the dischargepoint.

it is not necessary that the resistance be of exactly the criticalvalue. lf itis greater than the critical value, the only e'ect is, tiatthe discharge energy over it taires an unnecessarily long time, and eventhough theresistanceis ci" very much less than the critical value, theadvantages of my invention are obtained. For example, though theresistance used is cfa value of but one-tenth the critical falue, theoscillatory character is very materially changed for discharge is stilloscillatory the number of oscillations is strictly limited. Therefore,if the particular system to which my invention may be applied is capableor' standing the occurrence of a number of oscillations without thedevelopment of a. fault, .it is quite possible to use a. resistancehaving a 'alue .'ery considerably less than the critical value, erenthan one-tenth of the critical value. For this reason the wordapproximately hereinafter used in the specification aud'claims must hegiven a very. broad interpretation for I intend Ithe errpressionapproximately equaltol` thc critical value, and similar expressions, toinclude resistances oi" the critical value, resistances between thecritical value and even less than one-tenth of the critical value, andresistances oi a somewhat greater value than the critical value.

ln carrying out my invention with overhead transmission lines employingmetal towers or masts it is convenient to mount an airing' ring ou theinsulator carrying the conductor and connect this ring to the mast ortower through a resistance member so that 'the total resistance offeredto a discharge from or to that conductor is of approximately thecritical value. It is only necessary as will be understood, to connectthe resistance to whatever metallic body is most likely to receive thedischarge and insulate the metallic body except tor this connection. lnsystems using an overhead ground wire, a path or" approximately criticalresistance would be maintained between sanctions ol. the groumlfwiroamlprouml in the although the connue-tors are generally carriedonnecir-d to thc sheath ol' i manner illustrated, in principle, in gui-ei case olfunderground systems the i through eahles 'having nicizillicslieaths. ny discharge conductor "to ground,'thereiorej t lies placethrough the niet-allie sheath.

'Prfer with such eins, therefore, to carry ut iny invention o; keepingthe sheath out oi general connectiiu ufith the earth lijf inng it in anymanner und connecting t -e sheath to th earth at one. or more pointsthrough e, rosier ree er of approximately the enti, value. A discharge@round i i re, taires nlece to the sheath and through f c nnection toground.

novel features oi' my invention may embodied a ninnher of dil'erent conuclons. l'n the accompanying drawings he i' s i. 'WL ch forni a part oithis speciiication, fi. have illustrated diagrammatically two possibleconstructions embodying the novel fea.- tures of my invention in which:Fig. l illustrates one Way of applying my invention. to an overheadtransmission line, and Fig. 2 illustrates the principle of my inventionas applied to o. cable. p

In Fig. l the mast l. carries suitable arms @fior supporting theinsulators carrying the endnctors. T insulator 3 is carrie-d on a nattached to one of the arms or' the est.V On this insulator is carriedthe conductor-5. In carrying out 'my invention 'with such.overheadtransmission line it is sa lsactory to attach the resistanceinem-- her tothe inast at one end and the other end. to any metallichotly which is so loca 'ed as to mest likely receive the are from theadiacent conducton this .metallic body being insulated other thanthrough the resistance. lin this particular cas; l have illustrated anarcing ring' 6 of common construction, carl Electricallf,7 con the. conduetor 5 o at .least for any discharge which nia y tal-re place i'roni agiven part o'F the Conductor 5, the system as a whole being thusprotected against discharges where their occurrence would he especiallylangen ous or .uulesirahle.

ln Fig. i) is shown a cahle 'l0 haring the customary memllicuhratlnusually ci' lead. rThis cable .is showin.nim-ely tor purposes oiillustration7 as '.arryiug three conductors.

hr cable if; :L Cou- Leones.

Erein, one or he coiuhictors7 therelated fron: the ground other thanthrough the connectors. Now it is possible to attach a number of thegrounding connections to :i cable, preferably spacing 'themapproximately equal distances apart, the sheath of' the cable beingcontinuous electrically. It may also he desirable ut times to break thesheath into sections insulated from each otl'icr, as shown at In thiscase each section should have one or more grounded connections.

By this construction surges or oscillatory .discharges occurring on anyconductor of the cable are removed from the conductor and prevented frombuilding up voltage peaks, due to the :tact that the cable sheath formswith its path to ground an inductively related circuit of approximatelycritical resistance, whereby upon the occurrence of an oscillatorysurge, energy is induced from the conductor to the inductively relatedcircuit and such energy removed from the conductor to ground as onaperiodic discharve. Applying these principles of protection to cnoverhead ground Wire systeni, the ground wire would be connected toearth in sections, through resistance aths of approximately criticalvelue and therefore in like manner 'would remove from the conductor anyoscillatory disturhancerJ ucnperodic discharges.

llf'hct l. claim asx nv and desire to secure by Letters Pute.- vr eUnitedStates, isz-- l. The ecinlnnnticn with an electrical conductor, oimenons.; said conductor for loculi-zing discharges from said conductor,supports'ior said ineens providing pathsto vground from said means, andmeans conneetmgsmd'supports and said first mentioned means `coperatngwith said supports to provideypaths having i a. resistance eueient torender".dischargesl suiiicicnt to render all discharges over the 1.20

.saine non-os lhr'rory.`

3. The combination with an electrical cmnluctor7 of an insulatedmetallic member positioned relative to said conductor toreduc'e theinsulation value of said conductor at that point, a support for saidmember,

and a resistance between said inemher and sind support which combinedwith the resistance or said support provides path hav ing a totalresistance to conduct all dis- 130 located in proximity to f ehrges toground and render them nonn Witness whereof, have hereunto seteeciilatery. my hand this 12th day of May 191.3.

The combination With en electrical con- T dilater, an insulating supporttherefor, an ELMER E' F' CREGHT" iiicin'giring carried by Said support,and a Witnesses: connection to ground from said ring having HELENORFORD,

a resistance of applzoximately critical value. BENJAMIN B. HULL.

